FINALLY, IT IS a bafflement: only a little over a month ago a newly reconstituted president, itching to exert leadership and pounding his fist on the table to demonstrate as much, was presented to the American public. The voice was stronger, the gaze steadier, the visage -- along with the message -- less sunny. This was it. Mr. Carter would now reveal a tough, no-nonsense presidential streak to his character that many had feared was missing.

But that was July. This is August, and in the face of a policy debacle that has ugly and dangerous implications both at home and abroad and which can only be tamed by an exertion of presidential authority -- well, Mr. Carter is off campaigning on the Delta Queen, jogging, baby-kissing and playing for the cameras, looking ever more irrelevant to the deadly serious business at hand. This business includes 1) trying to contain and defuse the tensions that have been fomented between Jews and blacks as a conseuqence of the Andrew Young resignation, 2)restoring force and credibility to a Middle East policy that is evidently in shambles and 3)bringing order to his foreign policy establishment. Yesterday some kind of truce was announced in the warfare over diplomatic policy differences that was making all involved (including the country and the government) look foolish and weak.

Please understand. The issue here is not whether presidents deserve vacations. They do. But this trip, even by the White House spokesmen's own description, is at most only part vacation, the rest being billed as an energy-program selling venture. And, in any event, so far as direct presidential involvement in the confusion and tension caused by Andrew Young's resignation is concerned, the vacation had started several days before the president left Washington to board the Delta Queen in the first place. For it was not Ambassador Young, but the president who should have appeared and spoken directly about the events that had occurred and the considerations that led to the departure of Mr. Young. Instead, while still in Washington he let the whole painful public drama get started and gain momentum, while he added occasional odd comments from the sidelines-such as that he had only reluctantly accepted the resignation and that he was grateful for Mr. Young's continued political support. And then he sailed off into the sunset.

Can Mr. Carter have any idea what all this looks like on the nightly news when, after a full complement of foreboding and menacing statements issued from the capital, the U.N. and the Middle East, the now familiar tinkle of calliope-like music introduces the president of the United States and tells us how much fun he had today?

In behalf of Mr. Carter it is said that he is actually on a program-peddling mission, that his intention is to make his windfall profits tax in particular and his energy proposals in general so popular that they will be legislated by the Congress. This, presumable, is what the president meant in July when he said he thought he had been spending too much time managing the government and not enough leading the country. The proposition had an unpersuasive ring to it then-and the Mississippi riverboat gambol hasn't done a thing for its plausibility. Mr. Carter can best lead the country by managing his government, not by campaigning at dockside. He should take charge now, assert responsibility now, exert influence now to extinguish the flames of resentment associated with the Andrew Young departure and to get policy back on track.